Method of making boilers



Dec. 15,1925. 1 M 1,565,541

R. w. amcHFu-:LD 1

METHOD OF MAKING BOILERS Filed Aug. 4, 1925' 2 sheets-sheet 1 v Dec.15",1925.

R. w. BIRCHFIELD l METHOD OF MAKING BOILERS Filed Aug. 4, 1923" 1 2 Sheets-Sheet 2 ,J/ l f! Patented ec. 15, 1925..

niTEDTsrATES ROBERT w. BIBCHF'IELD, 0F :roLIET',Y1LL1NbIs.

Mn'rHonoF MAKING BoILnns. Y

Application -led August 4, 1923. Serial No. 655,637.

anduseful Improvements in Methods of the following is a Making Boilers, of which specification.

My invention relates to improvements inA meansandmethods of making parts of boilers and has special reference to improvements in the manufacture of inside wrap-` pers or combined crown and side sheets for return tube boilers of the kind-described and' claimed in my co-'pending re-issue application Serial lNumber 648,347 filed June 28, 1923, and this present invention is an improvement upon the methods described and claimed in my cci-pending applications, Serial Number 501,068 tiled September 16, 1921, and Serial Number 648,382 filed J une 28, 192s.

- The object of my invention is to enable the y manufacture of such boilers with a minimum expenditure of time and'labor and hence at a minimum cost.Y

Heretofore the inside wrapper sheets have required at least three operations all of which were arduous and required considerable time. A

The type of boiler to which my invention relates is ,known as the return tube or return iue boiler and consists of a main cylindrical body, a main combustion chamber below the main body portion and an auxiliaryicomv bustion chamber rising above one end of the main .combustion chamber., the side walls of the combustion chamber forming the in' side walls of side water legs for the boiler,

which depend from the main body portion.

The inside wrapper sheet, the production of which is the aim and object of my invention, consists of a single sheet formed to provide, a concave crown sheet, the inside sheets or walls of the water legs, and which are the side sheets of the -main combustion space of the boiler and continuations of which form the4 side sheets of the auxiliary combustion space.

Heretofore such inside wrappers have been formed by means ofheavy rolls and breaks in several steps and as described and claimed in'my said coi-pending applications, whereas by meansy of my present improvements Iam enabled to' eliminate substantially 90% of the time and an equal or greater percent-age ofthe labor.

Instead of forming the flat plate into the completed inside wrapper by the step by step forming method described andclaimed in my said co-pending method applications I combine all of the forming or bending operations into one so that instead of partially forming' the sheet in one operation viz forming the concave crown sheet andV then in a second operationreversing the 'direction of projection ofthe side parts to produce the downwardly extending side sheets, I now form the concave crown sheet and the downwardly-extending side sheets in one simultaneous operation.l

While I preferably pr'eliminarily c ut the sheetto provide the portionswhich are to form the' side sheets ofthe auxiliary combustion chamber I may and sometimes do delay this step until the wrapper yis formed and then I cut the sheet'if it has not been cut, and straighten or flatten out these parts.

' In the construction of my improved boiler,

as shown in my co-pending re-lssue application I close the lower ends of the side water legs by portions of the side sheets. bent to form' bottom flanges" and preferably I form these on the edges of the inside wrapper sheet before the main forming operation though obviously the formation of these fianges could be delayed until later or under some circumstances could be omitted altogether, as when` it is best to form them on the edges of the outer Wrapper.

My invention will be more readily understood by reference to the ,accompanying drawings in which I have illustrated a boiler of the kind to whichrmy invention relates and also have illustrated theone main step inmy improved method of production together with thev auxiliary steps of producing the portions which form the side sheets of the auxiliary combustion chamber.

In said drawings;

Figure 1, is a vertical, central, longitudinal, sectional view of a return tube boiler constructed in accordance with my invention; y

.50, outwardly turned bottom flanges 14 t'or :nished inside wrapper as it,v leaves the Figures 2 andY 3, are transverse, vertical, sectional views-in the lines 2 2 and 3-3 respectively of Figure 1g Figure 4,-is a perspective view of an inside'wrapper sheet in flat form, and showing the mrddle or crown portion cut at one end preparatory to forming side walls of an auxiliary combustion space and also showing bottom flanges dotted;

Figure 5, is a sectional view et the sheet in flat form shown in a press preparatory to being formed;

Figure 6, isa view similar-,to Figure 5 but showing the sheet as formed by the press;

Figure 7, is a perspective view oi the press; v g A Figure 8, is a'view similar to Figure4, except the sheet has not been cut; and Figure 9, is a perspective view` .of the sheet shown in Figure 3 as it leaves the press and' showing the crown sheet ,cut'preparator to the'last forming operation 151,1 said drawings V1 illustrates a boiler of the return iiue type and having a substantially cylindrical main part 2 Jfrom which depend side water legs 3 and end water legs 4, and 5.v The water legsenclose a combustion space beneath the main part of the boiler said combustion space comprising a main space 6 extending the length .ot the boiler and an auxiliary combustion space T rising above the rear end otthe main combustion space. rllhe gases of combustion rise from thema-in combustion space .y into vthe space 7 from which they flow forwardly through lower'tlues 8 to the forward end and return thru-upper dues 9. 1

rlhe shell ot f the boiler comprises a U- vshaped outerwiapper 10, a substantially U- I shaped inner wrapper 11,,and suitable endl sheets for closing the ends of thecombustion chambers and forming the end water legs. l

The inner wrapper sheet to the production of which this present invention appertainseonsists of a concave crown sheet portion 12 and depending substantially parallel side sheets 13 `and may be provided with closing the bottoms ot the side water legs of theboiler. The concave crown sheet portion 12 forms the lower part of the main cylindrical part of the boiler and is preferably curved on-the saine radius as the upper part 15 of the outer shell 10, as best shown in Figure 2. The main side sheet portions of the inner shell extend the length of the lire box but the crown sheet portion 12 only extends back to the forward end of the auxiliary combustion space 7 The side sheets 13 have upwardly extending parts 16 at their rear en ds which extend above the crown sheet portion to form the side sheets of the auxiliary combustion chamber 7.'

La messer `As the production of the vbottom 'lianges 14 onthe edges of the inner shell is optional 1 have shown them in dotted lines in the several iigures of the drawings which illustrate my improved method. This method consists in. providing a'iat sheet 17 such as illustrated in Figures 4 and 8 ot suitable dimensions.

l may as a preliminary step iirst cut the sheet on its transverse ncenter line as shown at 13 a distanceequalto-the length of thesheets 13. 1n such an operation the dies en-` gage only the crown sheet portion the severed parts 16 being troef-of the press and .A

consequently these portions are not deflected out oit' the planesyoit the side sheet portions but remain thereinand extend upwardly as shown in Figure 7 when the side sheet portions are in .depending position.'

rllhere. is one peculiarity about the dies and that is that it is practically impossible to lmake the upper die tol-force the side sheets inwardly beyond their true positions to allow for the inherent spring of' the metal and it has been found diHicult vto Aproduce these inner wrappers with the side sheets. parallel in this press operation. This diliiculty however has been met and overcome by making the middle portions 22v and 23 of the dies curved to slightly smaller radii than is desired on the finished wrapper and also making the. edge portions 24 and 25 which form the curves between the side sheets and the crown sheet likewise on slightly smaller radii that is required on the tinlshed wrapper.' rFhese parts arevmade on radii suliiciently smaller than the finished product so that'the inherent resilience ofY the plate when relieved of the pressure ot' the dies which tends to straighten both of these curves will be allowed tor.

rThe straighteningvotl the middle or crown sheet portion tends to swing the lower ends of the side sheets in too far and the straightening ot the edge curves tends to swing said lower ends outwardly Vand the dies are proportioned to equalize these tendencies and produce the inside wrapper `with parallel side sheets.

instead of using dies short enough to bend only the main crown sheet portion it is some times convenient to bend the whole width of the sheet and later on straighten outthe parts 16 for the side sheets o the auxiliary combustion space. When 1 form the inside wrapper in this latter `manner I preerably do not make the cuts 18 and 19 until after l the main bending operation. v

In Figure 8, I have illustrated a flat blank -sheet 26 which as in the former instance may or may not have n the bottom flanges 14 formed preliminarily. The sheet 26 is ing been made after vthe bending. -Thereafter theparts 16 are straightened `out and flattened and the naliorm of the-completed inner' wrapper is shown in Figure 7.

As indicated herein various changes can be made in the order ofthe steps of my improved method without going'beyond the scope of the invention 'and Aconsequently I do not limit my invention to the preferred sequence of operations.

I claim: p 1. The'herein described method of forming inside wrapper sheets of thekind described, which consists in providing a flatv sheet of the required dimensions, subjecting the sheet to pressure and thereby distorting the sheet outA of its flat condition and simultaneously forming a concave crownsheet and depending side sheets;

2. rlhe herein described method of forming inside wrapper sheets of'the kind described, which consists ,in providing' a Hat sheet of suitable dimensions, bending the sheet to form a concave crown sheet and simultaneously bending the sheet to form depending side sheets.

3. The herein described method of makl `'ing the inner shell of a boiler having an auX- iliary combustion space above one end of' a main combustion space which consists in providing a suitable flat blank, cutting the blank inwardly from one'end` on its transverse center line a distance equal to the length of the auxiliary combustion space then cutting the blank transversely at the inner end of thev first cut, then applying pressure to the blank and by means of the pressure applied in one bending operation. bringing the transverse end portions of *the blank into parallelism, the central portion intov a crown :sheet Idepending betweenthe side portions and during which bending operation the two severed portions ,are separated along the cuts and are brought into parallel relation inthe planes respectively'- or" said transverse end portions to form the sides of the auxiliary combustion space.

Il. The herein described steps in a method of forming an inside Shell for a boiler having an auxiliary combustion spaceaboveone end of la main combustion space, the provision of a suitable flat blank of a length equal to the length of the main combustion space and a width suiicient to extend from the lower edge of one side 'sheet up over fand down to the lower 'edge-of the opposite side sheet, cutting the blank inwardly from one bending the middle portion o'f the sheet to form a concave crown sheet and simultaneously bending the plate at the lateral edges of the crown sheet portion to bring the transverse end portions into parallelism 4to form the side sheets of the Vshell and by which bending operation the severed portions areA swung out into parallelism `and into the planes of the two side sheets respectively.

5i The herein described steps in a method of vforming an inside shell for a boiler having an auxiliary combustion space above one end of a main combustion space, the provision of a suitable flat blank of a length' .equal to the length of the main combustion spaceand a'width suliicient to eXtendrom the lower edge of one side sheet up and over and down-to the lower edge of the opposite side sheet, cutting the blank inwardly from o ne end on its transverse center line a distance equal to the length of the auX- iliary combustion space then .cutting the blank transversely at the inner end of the first cut, 'then depressing the middle p0rtion to form a concave crown' sheet and simultaneously depressing-the transverse end portions to bringA them; into parallelism to form the side sheets,A and by. which bending operation the severed portions are swung out into parallelism and. into the y planesiof the two side sheets respectively.

6. The method of making an inside wrapper for a. return flue boiler havingan auX- iliary combustion space abovefone end of the main combustion space which consists in 'providing a suitable flat sheet, bending the middle portion of the sheet to form a concave crown sheet and to simultaneously bring the edge portions of the sheet into parallelism. and subsequently straightening out portions of the middle portion into 'the planes .of 'the parallel portions for side sheets of the auxiliary'combustion spaces.

7. The herein described method of forming an inside wrapper of the kind described which-,consists in providing a suitablel flat sheet bending the middle portion to a curved v shape, having ashorter radius than the concave crown sheet desired and simultaneously bending the sheet at the Longitudinal., edges of said concave portion to extend the edge portions substantially parallel to each other and extending down from -theiniddle yconcave portionV and `said bends being on shorter radii than the linished bends desired and allowing the bends to assume their free un strainedv condition whereby said end portions extend parallel to each other..

8. lin apair' of dies for forming a sheet int-o an inside Wrapper of the kind described the bending portions of the dies being formed on shorter radii than the like porf tions of the finished Wrapper whereby said portions While in the dies are over bent sufficiently` to allow for the straigthening oi' theslieet due to its resiliency when released from the dies and whereby said side sheets arel maintained substantially parallel.

9. The herein described method or" formin;r an inside Wrapper sheet of the kind described, which consists in providing a suitable flat sheet, and simultaneously-bending the middle portion and the end portions of the sheet in the same direction vfrom the plane ot the sheet to form a concave crown sheet and depending substantially parallel side sheets.

10. The herein described steps in forming the inner shell Vof a boiler, having anfaux-4 iliary combustion space above one end of a main combustion space, ivhich method con sists in "providing a-suitable fiat sheet Inet-al blank which has certain portions to form main side sheets and other certain portions to Jform parts extending up from one end of the side sheets to form side sheets for the vauxiliary combustion space, bending the sheet to simultaneously form a concave crown sheet and depending parallel side `sheets andmaintainingl theV portions for the side sheets of the auxiliary combustion space Massei -to vforni parts extendingl up fromuone end of the side sheets te A:torni side sheets for the auxiliary combustion space, bending the sheet to simultaneously form 'a concave crown sheet and depending` side sheets, the. erown bein formed on a radins shorter thanv the inalform desired, and the free ends of the side sheets being formed in toward each other so as to incline the sheets upwardly and outwardly relatively to each other, each of the distortions being sufficient to allow tor the resiliency of the metal so that when the sheet is released from the bending pressure the crown will' be of the desired curvation and lthc sides will be parallel, andpreserving the auxiliary side sheet portions flatand in the planes of their respective main side sheet portions during' the forming operation. l

Signed at Chicago, Illinois, this 31st day 'of July, 1923.

ROBERT BRCHFELD. 

